Ultrastructure of canine toxic neutrophils.

Turpentine-induced inflammation was used as a model to study the ultrastructure of canine toxic neutrophils. Circulating toxic neutrophils contained large amounts of rough endoplasmic reticulum, but lamellar aggregates (Döhle bodies) were not observed. Cytoplasmic basophilia in Wright's stained neutrophils related to the persistence of rough endoplasmic reticulum and polyribosomes. Foamy vacuolation of the cytoplasm at the light microscopic level corresponded with irregular, electron-lucent areas which were not membrane bound. However, the presence of membrane remnants and myelin figures within lucent areas, as well as dilation and rupture of membranous structures in bone marrow precursors, indicated that these areas may have been membrane bound. In severely affected cells, there were few lysosomal granules. Early and intermediate neutrophils in the bone marrow of turpentine-injected dogs contained dilated and fragmented rough endoplasmic reticulum associated with irregular, electron-lucent areas in the cytoplasm and perinuclear space. Myelin figures were often in association with these electron-lucent areas. These findings indicated that cytoplasmic immaturity and cellular degeneration were involved in the morphogenesis of toxic neutrophils in the dog.